In 1992, Colorado voters adopted by initiative the TABOR limiting the power of the General Assembly to levy new taxes or increase tax rates without voter approval. In May 2011, various state legislators and other Colorado government officials and citizens filed suit in federal district court against Colorado Governor, John Hickenlooper, alleging that the limitations on the taxing authority of the General Assembly imposed by TABOR deprive the State of a republican form of government, in violation of the Guarantee and Supremacy Clauses, and in violation of the Equal Protection Clause, of the U.S. Constitution, the Colorado Enabling Act, and various clauses of the Colorado Constitution on the General Assembly’s authority to spend revenue.
In August 2011, the Colorado Attorney General, arguing that the state legislators lack standing and that the claims present “non-justiciable” political questions, moved to dismiss the lawsuit. In July 2012, the district court held that the members of the Colorado General Assembly have standing because their power to tax has been erased and that the claims may be decided by a court because the nature of a republican form of government can be decided by “judicially manageable standards” and is not a decision given to another branch of government. In August 2012, Colorado’s Attorney General filed a motion for review prior, to full trial before the district court (“interlocutory review”), by the Tenth Circuit, which the state legislators opposed. In November 2012, a three-judge panel of the Tenth Circuit agreed to hear the appeal.
The Governor filed his opening brief at the Tenth Circuit on February 1, 2013. On February 11, 2013, MSLF filed an amici curiae brief in support of the Governor on behalf of the Colorado Union of Taxpayers Foundation and 19 members of the Colorado General Assembly. The state legislators’ response brief was filed April 10, 2013. On April 24, 2013, the General Assembly filed an amicus curiae brief in support of the state legislators. On May 13, 2013, the Governor filed his reply. Oral Arguments were heard on September 23, 2013.
On March 7, 2014, a panel of the Tenth Circuit affirmed the district court's ruling and remanded for further proceedings. On April 4, 2014, the defendant filed a petition for rehearing en banc.
On April 8, 2014, the panel ordered the plaintiffs to file a response to defendant's petition. On May 7, 2014, the plaintiffs filed a response in opposition. On July 22, 2014, the petition was denied over the dissent of three judges.
On October 17, 2014, the Governor filed a petition for writ of certiorari. On November 20, 2014, MSLF filed an amicus curiae brief on behalf of the Colorado Union of Taxpayers Foundation and 22 members of the General Assembly in support of the petition. On November 21, 2014, the respondents filed an opposition brief. On June 30, 2015, the Supreme Court of the United States granted, vacated, and remanded the ruling of the Tenth Circuit for further consideration in light of the Court’s ruling in a related case.
On July 31, 2015, the parties filed supplemental briefs addressing whether the ruling of the Supreme Court of the United States in Arizona State Legislature v. Arizona Independent Redistricting Commn. required the Tenth Circuit to reconsider its previous decision. The same day, MSLF filed an amicus brief on behalf of the Colorado Union of Taxpayers Foundation, 44 current Colorado state legislators, and 7 former Colorado state legislators in support of Governor Hickenlooper. MSLF argued that Arizona State Legislature required the Tenth Circuit to dismiss the case. On August 20, 2015, the parties filed supplemental response briefs. On January 21, 2016, the Tenth Circuit heard oral argument.
On June 3, 2016, the Tenth Circuit held that the individual legislators did not have standing to challenge TABOR, as they alleged institutional injuries that can only be challenged by the entire legislature. On July 19, 2016, the Tenth Circuit denied the legislators’ petition for rehearing. On May 5, 2017, the Colorado federal district court dismissed the lawsuit holding that the plaintiffs lack standing, that is, the constitutional right to sue.